weather back at 6:00 p.m. >> okay, we do like that rain. >> i know. it's nice. >> thanks. hope to see you at 6:00. on our broadcast tonight, ambushed. an assassin opens fire on a u.s. general in afghanistan. the highest ranking officer killed in combat since vietnam. at least 14 others are wounded most of them americans. on edge. at some u.s. airports and hospitals, screening for possible ebola cases, as the second american victim returns home for treatment. getting closer to one of the biggest names in baseball as the feds make a big move tonight. could this blow the lid off on steroids once and for all? and taking a dive. daredevils finding a new extreme in one of the most beautiful places in america. now, the move to stop them. and who's right?

also, new rules for gluten-free food. "nightly news" begins now. good evening. a u.s. army two-star major general was killed today apparently when a member of the afghan armed forces turned his weapon on a visiting high ranking delegation at a military base there. major general harold green was an engineer by trade. a soldier and a scholar, with three master's degrees and a ph.d.. after numerous domestic postings in the army, he was second highest ranking u.s. military officer, presently posted in afghanistan. he becomes now the highest ranking officer killed in an overseas combat zone since the vietnam war. this incident happened just northwest of the city of kabul. tonight we begin at the pentagon with our correspondent jim miklaszewski. >> reporter: major general

harold green, a 34-year veteran, arrived in afghanistan for the first time this past january. his mission was to train and develop afghan military forces. it was one of those afghan soldiers who shot and killed general green today. a large group of american and coalition forces led by the general were at the afghan military academy examining a new water tank, when without warning, an afghan soldier from a nearby barracks opened fire with a machine gun, taking direct aim at the u.s. military officers, killing general green and wounding eight other americans. the gunman himself was soon killed by return fire. in all, 16 military were killed or wounded including two british, one german and four afghans. >> it's a terrible day, a terrible tragedy we haven't seen in the course of the last year or so. >> reporter: more than 100 american soldiers and marines have been killed by afghan soldiers in the so-called green on blue insider attacks.

but as american forces withdraw, the number of attacks has decreased. in 2012, 53 americans were killed in 38 attacks. last year that dropped to 16 and 10. this year, only 3 in 2 attacks, including today. >> the taliban will never stop trying to recruit afghans to conduct these kinds of attacks on -- not only americans, but also afghan soldiers that will continue forever. >> and afghanistan is still a war zone. so it's impossible to eliminate completely eliminate that threat. >> reporter: general green is the highest ranking u.s. military officer killed in a combat zone since vietnam when three american generals were killed. and since 9/11, a three-star army general was killed when terrorist hijackers flew an airliner into the pentagon. general green's family issued a statement late tonight from their home in virginia. the statement read that the family wants us to know that america lost a true hero today,

that he believed in what he was doing over there. green's wife is a retired army colonel. his son an active duty army officer at fort sill. the u.s. army has launched an investigation into his death. brian? >> jim miklaszewski on what became a sad day at the pentagon. jim, thanks. at hospitals and airports across our country tonight. they remain alert for people who may have symptoms consistent with the ebola virus. there were new scares and false alarms today, just as the second american patient has returned home for treatment under heavy protection. our national correspondent kate snow is at emery university in atlanta for us tonight. kate, good evening. >> reporter: good evening, brian. everyone was hoping that nancy writebol would walk into the hospital today just like the first ebola patient did. she is more than 20 years older. friends and family say fighting this dead thely disease for more than a week now has taken a toll. nancy writebol came home today.

landing just before noon at dobbins air reserve space. news choppers were overhead tracking every move. >> you see the ambulance on its way to emory university hospital. >> reporter: unmarked law enforcement vehicles surrounded the ambulance in a moving formation. >> we had s.w.a.t. teams, bomb teams, k-9. and, of course, we had assistance from university police and fbi as well, too. >> reporter: the paramedic driving and two paramedics in back wore haz-mat suits. nancy writebol arrived on a stretcher, encased from head to toe. >> nancy is still very weak, showing signs of progress and is moving in the right direction. and nancy had yogurt before she got on the airplane. >> reporter: bruce johnson spoke with nancy's husband david who's still arranging his own travel from liberia. >> a week ago he said, we were thinking about possible funeral arrangements, yet we kept our

faith. now we have a real reason to be hopeful. >> reporter: the evacuation of the two americans is being paid for by the relief organizations they work for. writebol's two sons came to atlanta to meet her. her son jeremy saying, he just needed to be with mom today. while she's now in a world class isolation unit, the family wants people to remember those suffering in west africa. >> i don't know if you know, but there are 50 doctors, liberian doctors for four million people of liberia. >> reporter: when writebol left liberia last night, there was no ambulance, just a pickup truck covered with plastic. kate snow, nbc news, atlanta. >> reporter: i'm dr. nancy snyderman at hartsfield-jackson atlanta international airport where 250,000 people pass through every day, including a daily flight from lagos,

nigeria, the latest hotspot in the western african ebola outbreak. for anyone arriving on an international flight. u.s. customs and border protection is the first line of defense. if someone appears ill, cdc quarantined officials will bring them here. this is the cdc's isolation room in atlanta. one of 20 like it around the country where infectious diseases are looked for and sometimes treated. in this refrigerator, anti-toxins to malaria, diphtheria, even botulism. but it's now ebola that anyone's worried about. anyone with fever, vomiting or diarrhea is put in a super isolation room. in addition to passenger surveillance, there are public health messages throughout the international terminal so that everybody knows what to look out for. a reminder tonight that ebola is still very rare, and unless you're working or fighting on the front lines, this disease is not something to be scared of, but something to know more about. brian? >> dr. nancy snyderman in

atlanta. kate snow before that on our coverage tonight. thank you both. we continue to monitor the weather. two tropical systems churning in both the atlantic and pacific. two systems are now making their way toward hawaii. hurricane iselle which is expected to weaken before hitting hawaii as a tropical storm. tropical storm julio right behind it. being called a double whammy for hawaii, which has been hit by just eight named storms since the 1950s. in the atlantic, bertha has now weakened to a tropical storm. moving on up the east coast. not expected to be a threat to land but it will make for rough surf and dangerous rip currents. just at a time when millions are vacationing at beaches all along the east coast. tonight over 1,000 firefighters battling two major fires burning in california. homes have burned. hundreds more are threatened. nbc's miguel almaguer got a bird's eye view of the danger.

he has a report tonight from burney, california. >> reporter: over 1100 firefighters on the front lines. the backbreaking work of containment. just over the ridge, two massive fires threatening the town of burney. over 700 homes at risk. today the chief for cal fire and the governor's office invited nbc news on an aerial tour. >> we're only in the first week of august. we have a long fire season ahead. >> reporter: a bird's eye view of the fire and its aftermath. when the fire hit this hillside, it took off like a blowtorch. just around the bend here there is more fuel to be burned. even in light rain, the threat is real. >> the game plan is to make an aggressive attack, get ahead with mother nature helping us out a bit. >> reporter: the two fires have burned more than 28,000 acres. eight homes have been lost. families like the murphys got out just in time.

firestorms swept through their neighborhood. the family unsure if their home is still standing. >> felt like the refugees running from this fire. >> two fires leaving a wake of destruction. a firefight far from over. miguel almaguer, nbc news, burney, california. major league baseball has a federal case on its hands and it involves drugs and a big connection to one of the biggest stars in the game in recent years. tonight a man who has admitted to supplying steroids has been arrested. he's agreed to plead guilty and said one of his biggest customers was alex rodrigez. our report tonight from our justice correspondent pete williams. >> reporter: investigators say he was the steroid connection for the highest paid player in baseball history, alex rodrigez of the yankees. federal drug agents arrested anthony bosh of key biscayne, florida, accusing him of selling

testosterone and other performance-enhancing drugs. among his customers were rodrigez, a dozen or so other major leaguers and nearly 20 florida high school students, supplied with drugs that came from the black market made by unknown suppliers. >> we're talking about some clown in his basement with a bucket and a burner, and a dangerously limited knowledge of chemistry. and these chemicals were going in our children's bodies. >> reporter: rodrigez is now under suspension for a year, the longest penalty ever in baseball for a doping violation. drug agents also arrested his cousin, accused of recruiting customers for bosh. bosh admitted today he introduced himself to players as dr. tony or dr. t even though he was not a doctor and had no authority to prescribe drugs. investigators say he also gave advice on how to take the drugs to minimize the chances of getting caught. in agreeing to plead guilty, bosh said he'll help the government's investigation. raising the possibility other players could be implicated. pete williams, nbc news at the justice department.

overseas now to the war in the middle east. there were hopes that this current cease-fire, number eight would be different. so far it's held. israel has used the break in fighting to take its ground forces out of gaza. after fighting that has now gone on for four weeks today. our chief foreign correspondent richard engel reports tonight from rafah in southern gaza. >> reporter: after a month of bitter fighting, israeli troops finally pulled out of gaza. gazans tried to put their lives back together. markets filled up, fishermen were back at work. so what changed? israel accomplished its stated goal of destroying hamas' tunnels. and just in time. because washington was losing patience as palestinian civilian casualties mounted. hamas, after a month of punishment, realized it was nearly without friends in the

region, especially egypt, its arab neighbor and former ally. this is gaza's crossing into egypt. throughout this war, hamas' main demand has been to open it. it's still closed. hamas has enemies in israel and in the military led government in egypt. egypt's president loathes hamas, which is part of the muslim brotherhood. he ousted the brotherhood from power in egypt and has been putting its members in jail. in gaza, as he picked through the rubble of his home today, shadi najar was as angry with egypt as he was with israel. egypt didn't help us, he said. sisi is an israeli agent. trapped between israeli bombs and tanks, and egypt's sealed border. hamas had little choice but to negotiate with its enemies. richard engel, nbc news, gaza. still ahead on this tuesday evening, a spectacular plunge. thrill seekers going to new extremes of one of the most majestic cases in the country.

now the fight is on over whether or not this kind of thing should be allowed. and later the new rules tonight for what foods can really be called gluten-free.

it's the summer of 2014 in the american west, and the conversation and debate in some of the most stunning places in our country, specifically eastern utah, is what some people are doing there that involves great danger and taking great risk. we get our report on this tonight from nbc's jacob rascon in moab, utah. >> reporter: they have always been the stunning centerpiece of utah's canyon country. but now moab's majestic arches are also a daredevil's dream. this youtube video posted two years ago, is credited with

fueling this extreme rope swinging craze. it's had some 23 million views so far and has made this free fall, one of the country's most popular stunts. >> that first step, it really takes your breath away, you want to scream, but it just won't come out. >> reporter: despite efforts to keep rope swinging safe, three people have died here in the last two years, including kyle, killed when he miscalculated the distance to the sand stone floor. >> they're basically hitting the rock, dying, and it's right in front of the kids. >> reporter: a top search and rescue deputy in what is called the front country. >> the overwhelming feeling is all of this should not occur in the front country. if you want to go out and kill yourself, do it in the back country. >> reporter: the bureau of land management is concerned about the daring rope swings turning deadly, and is considering a ban. their plan is to close the arch for two years for rope sports while they study whether it is safe and has a negative impact on the arch itself. the debate over access to this fragile land pits its caretakers

everywhere. and kyle stocking's mom lynn linda. >> even with my son kyle passing, there is no way i want it shut down. it's all about freedom. >> reporter: and finding a delicate balance between preserving nature's spectacular beauty and man's age old quest for adventure. jacob rascon, nbc news, moab, utah. when we come back here tonight, another video getting a lot of attention, this one's on the web caught by a young mom who had reason to suspect something or someone was up.

while a lot of perfectly healthy americans have chosen to go on a gluten-free diet for no apparent medical reason, the people with celiac disease must adhere to a gluten-free diet. effective today, there are new rules from the feds governing

which foods can say they are truly gluten-free. death valley was just uncomfortably warm. it was only 89. this is the first time since 1984 that a daytime high wasn't 90 degrees or above. put it this way, it was hotter in spokane and washington, and missoula, where the average high is 115. it was called the war to end all wars. it was not and did not and to mark the 100th anniversary of the start of the fighting of world war i, what an achingly beautiful remembrance of the great war at the tower of london. ceramic poppies placed there to remember the 1 million war dead in the u.k. poppies were also dropped by air this week. london blacked out last night in remembrance, a single candle lit the doorway of number 10 downing street.

the war killed close to 17 million people. fully 2% of the world's population. attention parents, if you've ever tried to cajole an amped up 2-year-old into going to bed on a hot summer night. take your worst experience and then double it. the video that's hit the web today shows a 21-year-old norwegian mom trying to coral her little wide awake helpers. leon and nathaniel, twin 2-year-olds who will not go down. we should also point out it's nighttime, though it doesn't look like it. it's sunny for 16 and a half hours a day these days in norway. and in the summer it's hot. and suspecting she was getting played. she set up a time lapse camera, and the video is being played around the world. when we come back here tonight, andrea mitchell at an extraordinary summer camp where something very special is going on there right now.

our making a difference report tonight is about what's happening at a summer camp in maine. where kids do all things summer camps offer, but something

special is taking place at this particular place. because of the kids who are there and what's happening right now halfway around the world. nbc's andrea mitchell has our report. ♪ >> reporter: far from the war zone, israeli teenagers arrive in maine to meet their new bunk mates, palestinians. seeds of peace for years bringing together teenagers from conflict zones for three weeks of soccer, tag, water sports. but never during a war so brutal with emotions so raw. >> destroy her, salma. >> reporter: 17-year-old salma, a second year camper from gaza. you're here at a time of war back home. how complicated does that make it for you? >> it's so complicated for me and confusing, because i'm here having fun, laughing. while the children in gaza are dying.

>> also 17, yoran, just a year away from military service in the army. >> people think it's not the right time to talk about peace. we say the opposite, this is exactly the right time. >> what makes this place so special is structured dialogue. private conversation between the palestinian and israeli campers, where they're free to express their pain, their anger, even their hatred. and try to start working through it. >> looking at this as a long term investment, that feels very frustrating in moments like this. >> reporter: most like this first time camper have spent their whole lives thinking of the other as the enemy. >> like for me, they are terrorists. >> but after three days, his israeli bunk mate is listening. >> maybe what you think about us is wrong. maybe not all of them are mean. not all of them are terrorists. >> it's a conversation just getting started. >> the other side is also people, they have a faith, a personality. >> if a soldier is going to carry a gun and point at a palestinian, i need to make him

think twice, count to three before he does it. >> reporter: could it be they're onto something good for the middle east from a camp site in the woods? andrea mitchell, nbc news, maine. that's our broadcast on a tuesday night. thank you for being here with us. i'm brian williams, we, of course, hope to see you right back here tomorrow evening. course, hope to see you right back here tomorrow evening. good night. -- captions by vitac -- www.vitac.com nbc bay area news starts now. right now at 6:00, serious security questions after another stow away sneaks on board a flight. i'm janelle wang in for raj mathai. >> and i'm jessica aguirre. this is a developing story. we learned that a woman who breached security and repeatedly attempted to board flights has at last succeeded. >> she got past security and

onto a plane without a ticket. nbc bay area's chief investigative reporter tony kovaleski has more about where she went and how she was discovered. >> reporter: unbelievable is one word you'd use to describe what happened last night. it's not the first time it's happened with this 62-year-old woman. we know tsa through sources and southwest airlines have been spending several hours, going through, combing through the video at the airport to try to figure out exactly what happened. let's show you video taken a few minutes ago from inside san jose's airport. this is the check point. the tsa is saying that this afternoon they've already made minor changes to the document checking area to increase security there. here's what happened last night. 62-year-old marian hartman breached security here at san jose's airport. she successfully